Modulation and demodulation method, device and equipment based on LoRa

Abstract

The invention provides a LoRa-based modulation and demodulation method, device and equipment, and relates to the technical field of Internet communication, and the method comprises the steps: obtaining a receiving signal, filtering the receiving signal through a band-pass filter, obtaining a first filtering signal, filtering the first filtering signal through a low-pass filter, and obtaining a second filtering signal; the method comprises the following steps: acquiring a first filtering signal, sampling according to the cut-off frequency of a low-pass filter, performing compounding and FFT (Fast Fourier Transform) to obtain a second filtering signal, determining the position of the maximum amplitude spectrum value in the second filtering signal as a demodulation symbol, and adjusting a spreading factor and / or sending time corresponding to the demodulation symbol based on a conflict monitoring signal to obtain a conflict monitoring signal. And the adjusted demodulation symbol is sent to a demodulation end for demodulation, so that the bit error rate in the signal transmission process is reduced, and the reliability of signal transmission is improved.

Description

Technical Field

[0001] The present invention relates to the field of Internet communication technology, and in particular to a modulation and demodulation method, device and equipment based on LoRa. Background Art

[0002] Compared with ground IoT communication, satellite IoT communication aims to achieve seamless coverage and secure and reliable real-time communication on a global scale. This is because it is not restricted by factors such as urban planning, ground topography (rivers, mountains, lakes), and the influence of weather and climate. The continuous advancement of information technology has driven the rapid development of the Internet of Things. As a low-power wide area network (Low Power WAN, LPWAN) wireless communication technology, LoRa (Long Range) communication technology has a lot of room for development in IoT application scenarios, solving the problem that long communication distance and low power consumption cannot be taken into account in traditional IoT technology. However, with the widespread application of LoRa technology, the number of terminal nodes in the network has increased rapidly, the network throughput has dropped significantly, the scalability has decreased, and even the current data packet is likely to collide with other data packets, resulting in damage or loss of data packets. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that the terminal nodes in the current network are rapidly increasing, the network throughput is significantly reduced, and the data packets are likely to collide with other data packets, thereby causing damage or loss of data packets. The present invention provides a modulation and demodulation method, device and equipment based on LoRa.

[0004] The technical solution of the embodiment of the present application is implemented as follows:

[0005] A first aspect of an embodiment of the present application provides a modulation and demodulation method based on LoRa, including:

[0006] Acquire a received signal, and filter the received signal using a bandpass filter to obtain a first filtered signal;

[0007] The first filtered signal is filtered through a low-pass filter, and after being sampled at the cut-off frequency of the low-pass filter, a composite signal and an FFT transform are performed to obtain a second filtered signal, and the position of the maximum value of the amplitude spectrum in the second filtered signal is determined as a demodulation symbol;

[0008] The spreading factor and / or sending time corresponding to the demodulation symbol is adjusted based on the conflict monitoring signal, and the adjusted demodulation symbol is sent to the demodulation end for demodulation.

[0009] Optionally, filtering the received signal by using a bandpass filter to obtain a first filtered signal includes: multiplying the received signal by two orthogonal baselines to obtain:

[0010]

[0011] Wherein, the frequency of the received signal (f0+f k,t )∈[f0,+BW], is the last chirp symbol at t→T c The phase at time, T c is the chirp symbol transmission time.

[0012] Optionally, the first filtered signal is filtered by a low-pass filter, and the signal obtained by sampling at the cutoff frequency of the low-pass filter is:

[0013]

[0014] Optionally, the sampling at the cutoff frequency of the low-pass filter and then performing compounding and FFT transformation to obtain a second filtered signal includes:

[0015] The two signals obtained by sampling are used as the real part and the imaginary part respectively to construct a complex signal, and the complex signal is subjected to FFT transformation to obtain a second filtered signal.

[0016] Optionally, adjusting the spreading factor and / or sending time corresponding to the demodulated symbol based on the conflict monitoring signal includes:

[0017] If the conflict monitoring signal indicates that the demodulated symbol conflicts with other data to be transmitted, a spreading factor and / or a sending time corresponding to the demodulated symbol is adjusted.

[0018] A second aspect of an embodiment of the present application provides a LoRa-based modulation and demodulation device, including: a first filtering module, a second filtering module and an adjustment module, wherein:

[0019] The first filtering module is configured to obtain a received signal and filter the received signal using a bandpass filter to obtain a first filtered signal;

[0020] The second filtering module is configured to filter the first filtered signal through a low-pass filter, sample it at the cutoff frequency of the low-pass filter, perform compounding and FFT transformation to obtain a second filtered signal, and determine the position of the maximum value of the amplitude spectrum in the second filtered signal as a demodulation symbol;

[0021] The adjustment module is configured to adjust the spreading factor and / or sending time corresponding to the demodulation symbol based on the conflict monitoring signal, and send the adjusted demodulation symbol to the demodulation end for demodulation.

[0022] Optionally, the second filtering module is further configured as follows:

[0023] The two signals obtained by sampling are used as the real part and the imaginary part respectively to construct a complex signal, and the complex signal is subjected to FFT transformation to obtain a second filtered signal.

[0024] Optionally, the adjustment module is specifically configured as follows:

[0025] If the conflict monitoring signal indicates that the demodulated symbol conflicts with other data to be transmitted, a spreading factor and / or a sending time corresponding to the demodulated symbol is adjusted.

[0026] A third aspect of an embodiment of the present application provides an electronic device, comprising a processor and a memory; the memory stores a computer program, wherein the computer program, when executed by the processor, implements the LoRa-based modulation and demodulation method described in the first aspect.

[0027] A fourth aspect of an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect.

[0028] Compared with the prior art, the technical solution provided by this application has the following beneficial effects:

[0029] The present invention provides a modulation and demodulation method, device and equipment based on LoRa, which obtains a received signal and filters the received signal by using a bandpass filter to obtain a first filtered signal, filters the first filtered signal by a low-pass filter, and performs compounding and FFT transformation after sampling at the cut-off frequency of the low-pass filter to obtain a second filtered signal, and determines the position of the maximum value of the amplitude spectrum in the second filtered signal as a demodulation symbol, adjusts the spreading factor and / or the sending time corresponding to the demodulation symbol based on a conflict monitoring signal, and sends the adjusted demodulation symbol to a demodulation end for demodulation, thereby reducing the bit error rate of the signal transmission process and improving the reliability of signal transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A flowchart of a LoRa-based modulation and demodulation method provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of the structure of a LoRa-based modulation and demodulation device provided in an embodiment of the present application;

[0032] Figure 3 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] Below, embodiments of the present application will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present application. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present application.

[0034] The terms used herein are only for describing specific embodiments and are not intended to limit the present application. The terms "include", "comprising", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0035] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0036] Some block diagrams and / or flow charts are shown in the accompanying drawings. It should be understood that some blocks or combinations thereof in the block diagrams and / or flow charts may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that these instructions, when executed by the processor, may create a device for implementing the functions / operations described in these block diagrams and / or flow charts.

[0037] In some embodiments, see Figure 1 , Figure 1 A schematic diagram of a flow chart of a LoRa-based modulation and demodulation method provided in an embodiment of the present application; the LoRa-based modulation and demodulation method provided in an embodiment of the present application includes:

[0038] S110, acquiring a received signal, and filtering the received signal using a bandpass filter to obtain a first filtered signal.

[0039] In this embodiment, the received signal may be a chirp signal. A band-pass filter (BPF) is a filter that allows signals within a specific frequency band to pass through while suppressing signals outside the frequency band. Here, the signal frequency band is retained by the band-pass filter and out-of-band noise is filtered out.

[0040] In one example, a period of chirp signal is uniformly quantized into N segments along the time axis, and the chirp signal is cyclically shifted N times along the time axis, each shift being T cN time length, to represent N different symbols. The waveform function of the chirp signal with modulation symbol k can be expressed as:

[0041]

[0042] in, is the last chirp symbol at t→T c The phase of It can ensure that the entire chirp symbol stream is phase continuous, thereby avoiding the introduction of high-order harmonic noise due to waveform jumps.

[0043] In some embodiments, S110, filtering the received signal using a bandpass filter to obtain a first filtered signal includes: multiplying the received signal with two orthogonal baselines to obtain:

[0044]

[0045] Among them, the frequency of the received signal (f0+f k,t )∈[f0,+BW], is the last chirp symbol at t→T c The phase at time, T c is the chirp symbol transmission time.

[0046] S120, filtering the first filtered signal through a low-pass filter, and performing compounding and FFT transformation after sampling at the cutoff frequency of the low-pass filter to obtain a second filtered signal, and determining the position of the maximum value of the amplitude spectrum in the second filtered signal as a demodulation symbol.

[0047] The first filtered signal is passed through a low-pass filter to further remove high-frequency noise or unwanted signal components. The cutoff frequency of this low-pass filter can be selected according to the signal characteristics and demodulation requirements. The filtered signal is sampled with the cutoff frequency of the low-pass filter (or twice, depending on the Nyquist sampling theorem) as a reference, and then the composite signal is subjected to a fast Fourier transform (FFT) to convert the signal from the time domain to the frequency domain.

[0048] In some embodiments, S120, the first filtered signal is filtered by a low-pass filter, and the signal sampled at the cutoff frequency of the low-pass filter is:

[0049]

[0050] In some embodiments, S120, sampling at the cutoff frequency of the low-pass filter and then performing a composite and FFT transformation to obtain a second filtered signal includes:

[0051] The two signals obtained by sampling are used as the real part and the imaginary part respectively to construct a complex signal, and the complex signal is transformed by FFT to obtain a second filtered signal.

[0052] In this embodiment, the low-pass filtered signal is synchronously sampled to ensure synchronization of the two signals. On this basis, the two signals are used as the real part and the imaginary part to construct a complex signal, which is then fast Fourier transformed to obtain a frequency domain signal.

[0053] S130, adjusting the spreading factor and / or sending time corresponding to the demodulation symbol based on the conflict monitoring signal, and sending the adjusted demodulation symbol to the demodulation end for demodulation.

[0054] CO-SF (Common Spreading Factor) interference occurs when packets sent from different LoRa terminals use the same carrier frequency (CF) and spreading factor (SF), and overlap in transmission time. Since the same CF and SF are used, this interference will definitely lead to transmission conflicts. Inter-SF (Inter-Spreading Factor) interference occurs when packets sent from different LoRa terminals use the same carrier frequency but different spreading factors, and overlap in transmission time. This interference is caused by the imperfect orthogonality of LoRa symbols. These situations can be monitored by the gateway.

[0055] In some embodiments, S130, adjusting the spreading factor and / or sending time corresponding to the demodulated symbol based on the conflict monitoring signal includes:

[0056] If the conflict monitoring signal indicates that the demodulated symbol conflicts with other data to be transmitted, the spreading factor and / or the sending time corresponding to the demodulated symbol are adjusted.

[0057] In this embodiment, if the conflict monitoring signal indicates that the demodulated symbol conflicts with other data to be transmitted, the spreading factor may be adjusted alone, or the sending time of the demodulated symbol may be adjusted alone, or both the spreading factor and the sending time may be adjusted simultaneously.

[0058] Taking the example of adjusting the sending time of the demodulation symbol separately, if the conflict monitoring signal indicates that the demodulation symbol conflicts with other data to be transmitted, the demodulation end will return a NACK signal. Based on the monitored NACK signal, the data conflict can be determined, and then a random time is selected to retransmit the demodulation symbol, or the demodulation symbol is retransmitted according to a preset time until the NACK signal returned by the demodulation end is not detected within the effective monitoring period.

[0059] This embodiment obtains a received signal and filters the received signal using a bandpass filter to obtain a first filtered signal, filters the first filtered signal through a low-pass filter, and samples it at the cutoff frequency of the low-pass filter and performs a composite and FFT transformation to obtain a second filtered signal, and determines the position of the maximum value of the amplitude spectrum in the second filtered signal as a demodulation symbol, adjusts the spreading factor and / or emission time corresponding to the demodulation symbol based on a conflict monitoring signal, and sends the adjusted demodulation symbol to a demodulation end for demodulation, thereby reducing the bit error rate of the signal transmission process and improving the reliability of signal transmission.

[0060] In some embodiments, see Figure 2 , Figure 2 A schematic diagram of the structure of a LoRa-based modulation and demodulation device provided in an embodiment of the present application; a LoRa-based modulation and demodulation device 200 provided in an embodiment of the present application comprises: a first filtering module 210, a second filtering module 220 and an adjustment module 230, wherein:

[0061] The first filtering module 210 is configured to obtain a received signal and filter the received signal using a bandpass filter to obtain a first filtered signal.

[0062] The second filtering module 220 is configured to filter the first filtered signal through a low-pass filter, sample it at the cutoff frequency of the low-pass filter, perform compounding and FFT transformation, obtain a second filtered signal, and determine the position of the maximum value of the amplitude spectrum in the second filtered signal as a demodulation symbol.

[0063] The adjustment module 230 is configured to adjust the spreading factor and / or the sending time corresponding to the demodulation symbol based on the conflict monitoring signal, and send the adjusted demodulation symbol to the demodulation end for demodulation.

[0064] In some embodiments, the first filtering module 210 is specifically configured to multiply the received signal by two orthogonal baselines to obtain:

[0065]

[0066] Among them, the frequency of the received signal (f0+f k,t )∈[f0,+BW], is the last chirp symbol at t→T c The phase at time, T c is the chirp symbol transmission time.

[0067] In some embodiments, the signal sampled at the cutoff frequency of the low-pass filter is:

[0068]

[0069] In some embodiments, the second filtering module 220 is specifically configured as follows:

[0070] The two signals obtained by sampling are used as the real part and the imaginary part respectively to construct a complex signal, and the complex signal is transformed by FFT to obtain a second filtered signal.

[0071] In some embodiments, the adjustment module 230 is specifically configured as follows:

[0072] If the conflict monitoring signal indicates that the demodulated symbol conflicts with other data to be transmitted, the spreading factor and / or the sending time corresponding to the demodulated symbol are adjusted.

[0073] The LoRa-based modulation and demodulation device provided in the embodiment of the present application is based on the above-mentioned LoRa-based modulation and demodulation method, which will not be described again here to avoid repetition.

[0074] It should be noted that the LoRa-based modulation and demodulation device provided in the embodiment of the present application and the LoRa-based modulation and demodulation method provided in the embodiment of the present application are based on the same application concept. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned LoRa-based modulation and demodulation method, and the repeated parts will not be repeated.

[0075] In some embodiments, see Figure 3 , Figure 3 The electronic device 300 provided in the embodiment of the present application includes a processor 310 and a memory 320; the memory 320 stores a computer program, wherein the computer program implements the above-mentioned LoRa-based modulation and demodulation method when executed by the processor.

[0076] Specifically, the processor 310 may include, for example, a general-purpose microprocessor, an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 310 may also include an onboard memory for cache purposes. The processor 310 may be a single processing unit or multiple processing units for executing different actions of the method flow according to the embodiment of the present application.

[0077] The memory 320 may be any medium capable of containing, storing, conveying, propagating or transmitting instructions. For example, the memory 320 may include, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared or semiconductor system, device, component or propagation medium. Specific examples of the memory 320 include: a magnetic storage device, such as a magnetic tape or a hard disk (HDD); an optical storage device, such as a compact disk (CD-ROM); a random access memory (RAM) or flash memory; and / or a wired / wireless communication link.

[0078] The present application also provides a computer-readable medium on which a computer program is stored, and when the program is executed by a processor, the above-mentioned LoRa-based modulation and demodulation method is implemented. The computer-readable medium may be included in the device / system described in the above embodiment; or it may exist alone without being assembled into the device / system. The above-mentioned computer-readable medium carries one or more programs, and when the above-mentioned one or more programs are executed, the method according to the embodiment of the present application is implemented.

[0079] According to an embodiment of the present application, a computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium or any combination of the two. A computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to, an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, device or device. In the present application, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, in which a computer-readable program code is carried. This propagated data signal may take a variety of forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate or transmit a program for use by or in conjunction with an instruction execution system, apparatus or device. The program code contained on the computer-readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wired, optical cable, radio frequency signal, etc., or any suitable combination of the above.

[0080] Those skilled in the art will appreciate that the features described in the various embodiments and / or claims of the present application may be combined and / or combined in a variety of ways, even if such combinations or combinations are not explicitly described in the present application. In particular, without departing from the spirit and teachings of the present application, the features described in the various embodiments and / or claims of the present application may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present application. Therefore, the scope of the present application should not be limited to the above-described embodiments, but should be determined not only by the appended claims, but also by the equivalents of the appended claims.

Claims

1. A modulation and demodulation method based on LoRa, characterized in that: include: Acquire a received signal, and filter the received signal using a bandpass filter to obtain a first filtered signal; The first filtered signal is filtered through a low-pass filter, and after being sampled at the cut-off frequency of the low-pass filter, a composite signal and an FFT transform are performed to obtain a second filtered signal, and the position of the maximum value of the amplitude spectrum in the second filtered signal is determined as a demodulation symbol; The spreading factor and / or sending time corresponding to the demodulation symbol is adjusted based on the conflict monitoring signal, and the adjusted demodulation symbol is sent to the demodulation end for demodulation.

2. The LoRa-based modulation and demodulation method according to claim 1, characterized in that: The step of filtering the received signal by a bandpass filter to obtain a first filtered signal includes: multiplying the received signal by two orthogonal baselines to obtain: Wherein, the frequency of the received signal (f0+f k,t )∈[f0,+BW], is the last chirp symbol at t→T c The phase at time, T c is the chirp symbol transmission time.

3. The LoRa-based modulation and demodulation method according to claim 2, characterized in that: The first filtered signal is filtered by a low-pass filter and the signal obtained by sampling at the cut-off frequency of the low-pass filter is:

4. The LoRa-based modulation and demodulation method according to claim 1, characterized in that: The step of sampling at the cutoff frequency of the low-pass filter and performing compounding and FFT transformation to obtain a second filtered signal comprises: The two signals obtained by sampling are used as the real part and the imaginary part respectively to construct a complex signal, and the complex signal is subjected to FFT transformation to obtain a second filtered signal.

5. The LoRa-based modulation and demodulation method according to claim 1, characterized in that: The adjusting the spreading factor and / or sending time corresponding to the demodulation symbol based on the conflict monitoring signal includes: If the conflict monitoring signal indicates that the demodulated symbol conflicts with other data to be transmitted, a spreading factor and / or a sending time corresponding to the demodulated symbol is adjusted.

6. A LoRa-based modulation and demodulation device, characterized in that: include: A first filtering module, a second filtering module and an adjustment module, wherein: The first filtering module is configured to obtain a received signal and filter the received signal using a bandpass filter to obtain a first filtered signal; The second filtering module is configured to filter the first filtered signal through a low-pass filter, sample it at the cutoff frequency of the low-pass filter, perform compounding and FFT transformation to obtain a second filtered signal, and determine the position of the maximum value of the amplitude spectrum in the second filtered signal as a demodulation symbol; The adjustment module is configured to adjust the spreading factor and / or sending time corresponding to the demodulation symbol based on the conflict monitoring signal, and send the adjusted demodulation symbol to the demodulation end for demodulation.

7. The LoRa-based modulation and demodulation system according to claim 6, characterized in that: The second filtering module is further configured as follows: The two signals obtained by sampling are used as the real part and the imaginary part respectively to construct a complex signal, and the complex signal is subjected to FFT transformation to obtain a second filtered signal.

8. The LoRa-based modulation and demodulation system according to claim 6, characterized in that: The adjustment module is specifically configured as follows: If the conflict monitoring signal indicates that the demodulated symbol conflicts with other data to be transmitted, a spreading factor and / or a sending time corresponding to the demodulated symbol is adjusted.

9. An electronic device comprising a processor and a memory; the memory stores a computer program, wherein: When the computer program is executed by the processor, the LoRa-based modulation and demodulation method according to any one of claims 1 to 5 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, wherein when the program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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